The cyclic undecapeptide, cyclosporin H, is a potent inhibitor of formyl-Met-Leu-Phe (FMLP)-induced superoxide anion (O2-) formation in human neutrophils. Cyclosporin H inhibits FMLP binding in HL-60 membranes with a Ki of 0.1 μM. Cyclosporin H inhibits activation by FMLP of high affinity GTPase (the enzymatic activity of alpha-subunits of heterotrimeric regulatory guanine nucleotide-binding proteins) in HL-60 membranes with a Ki of 0.79 μM. Cyclosporin H inhibits the stimulatory effects of FMLP on cytosolic Ca concentration ([Ca]i), O2- formation, and beta-glucuronidase release with Ki values of 0.08, 0.24, and 0.45 μM, respectively.
Medlife has not independently confirmed the accuracy of these methods. They are for reference only.